//===================================================================================
// Microsoft patterns & practices
// Composite Application Guidance for Windows Presentation Foundation and Silverlight
//===================================================================================
// Copyright (c) Microsoft Corporation.  All rights reserved.
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
// FITNESS FOR A PARTICULAR PURPOSE.
//===================================================================================
// The example companies, organizations, products, domain names,
// e-mail addresses, logos, people, places, and events depicted
// herein are fictitious.  No association with any real company,
// organization, product, domain name, email address, logo, person,
// places, or events is intended or should be inferred.
//===================================================================================
using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;
using Microsoft.Practices.Prism.Properties;
using Microsoft.Practices.ServiceLocation;
using System.Reflection;
using System.Globalization;

namespace Microsoft.Practices.Prism.Regions
{
	/// <summary>
	/// Defines a factory that allows the registration of the default set of <see cref="IRegionBehavior"/>, that will
	/// be added to the <see cref="IRegionBehaviorCollection"/> of all <see cref="IRegion"/>s, unless overridden on a 'per-region' basis. 
	/// </summary>
	[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1710:IdentifiersShouldHaveCorrectSuffix", Justification = "It is more of a factory than a collection")]
	public class RegionBehaviorFactory : IRegionBehaviorFactory
	{
		private readonly IServiceLocator serviceLocator;
		private readonly Dictionary<string, Type> registeredBehaviors = new Dictionary<string, Type>();

		/// <summary>
		/// Initializes a new instance of <see cref="RegionBehaviorFactory"/>.
		/// </summary>
		/// <param name="serviceLocator"><see cref="IServiceLocator"/> used to create the instance of the behavior from its <see cref="Type"/>.</param>
		public RegionBehaviorFactory(IServiceLocator serviceLocator)
		{
			this.serviceLocator = serviceLocator;
		}

		/// <summary>
		/// Adds a particular type of RegionBehavior if it was not already registered. The <paramref name="behaviorKey"/> string is used to check if the behavior is already present
		/// </summary>
		/// <param name="behaviorKey">The behavior key that's used to find if a certain behavior is already added.</param>
		/// <param name="behaviorType">Type of the behavior to add.</param>
		public void AddIfMissing(string behaviorKey, Type behaviorType)
		{
			if (behaviorKey == null)
			{
				throw new ArgumentNullException("behaviorKey");
			}

			if (behaviorType == null)
			{
				throw new ArgumentNullException("behaviorType");
			}

			// Check if the type is a IRegionBehavior
			if (!typeof(IRegionBehavior).GetTypeInfo().IsAssignableFrom(behaviorType.GetTypeInfo()))
			{
				throw new ArgumentException(
					string.Format(
					CultureInfo.InvariantCulture,
					Resources.CanOnlyAddTypesThatInheritIFromRegionBehavior,
					behaviorType.Name),
					"behaviorType");
			}

			// Only add the behaviorKey if it doesn't already exists. 
			if (this.registeredBehaviors.ContainsKey(behaviorKey))
			{
				return;
			}

			this.registeredBehaviors.Add(behaviorKey, behaviorType);
		}

		/// <summary>
		/// Creates an instance of the behavior <see cref="Type"/> that is registered using the specified key.
		/// </summary>
		/// <param name="key">The key that is used to register a behavior type.</param>
		/// <returns>A new instance of the behavior. </returns>
		public IRegionBehavior CreateFromKey(string key)
		{
			if (!this.ContainsKey(key))
			{
				throw new ArgumentException(
					string.Format(
					CultureInfo.InvariantCulture,
					Resources.TypeWithKeyNotRegistered,
					key),
					"key");
			}

			return (IRegionBehavior)this.serviceLocator.GetInstance(this.registeredBehaviors[key]);
		}


		/// <summary>
		/// Returns an enumerator that iterates through the collection.
		/// </summary>
		/// <returns>
		/// A <see cref="T:System.Collections.Generic.IEnumerator`1" /> that can be used to iterate through the collection.
		/// </returns>
		/// <filterpriority>1</filterpriority>
		public IEnumerator<string> GetEnumerator()
		{
			return this.registeredBehaviors.Keys.GetEnumerator();
		}

		/// <summary>
		/// Returns an enumerator that iterates through a collection.
		/// </summary>
		/// <returns>
		/// An <see cref="T:System.Collections.IEnumerator" /> object that can be used to iterate through the collection.
		/// </returns>
		/// <filterpriority>2</filterpriority>
		IEnumerator IEnumerable.GetEnumerator()
		{
			return this.GetEnumerator();
		}

		/// <summary>
		/// Determines whether a behavior with the specified key already exists.
		/// </summary>
		/// <param name="behaviorKey">The behavior key.</param>
		/// <returns>
		/// <see langword="true"/> if a behavior with the specified key is present; otherwise, <see langword="false"/>.
		/// </returns>
		public bool ContainsKey(string behaviorKey)
		{
			return this.registeredBehaviors.ContainsKey(behaviorKey);
		}
	}
}